feat(boss-engine): 增加项目派生命令

新增 fork-boss-engine，从 AbyssBossEngine 源项目生成独立 BOSS 模组，并重建 UUID、命名空间和脚本包。

校验项目名称与命名空间，同时阻止输出目录落入源目录，避免路径穿越和递归复制。

src/boss_engine/copy.rs

@@ -0,0 +1,35 @@
+use crate::error::Result;
+use std::path::Path;
+
+/// 递归复制项目目录，排除指定的目录名和文件名。用于 fork 的项目复制。
+pub fn copy_dir_filtered(
+    src: &Path,
+    dst: &Path,
+    exclude_dirs: &[&str],
+    exclude_files: &[&str],
+) -> Result<()> {
+    std::fs::create_dir_all(dst)?;
+
+    for entry in std::fs::read_dir(src)? {
+        let entry = entry?;
+        let entry_path = entry.path();
+        let file_name = entry.file_name();
+        let name_str = file_name.to_string_lossy();
+
+        if entry_path.is_dir() {
+            if exclude_dirs.contains(&name_str.as_ref()) {
+                continue;
+            }
+            let dest_path = dst.join(&file_name);
+            copy_dir_filtered(&entry_path, &dest_path, exclude_dirs, exclude_files)?;
+        } else if entry_path.is_file() {
+            if exclude_files.contains(&name_str.as_ref()) {
+                continue;
+            }
+            let dest_path = dst.join(&file_name);
+            std::fs::copy(&entry_path, &dest_path)?;
+        }
+    }
+
+    Ok(())
+}

src/boss_engine/mod.rs

@@ -0,0 +1,114 @@
+pub mod copy;
+
+use std::path::{Path, PathBuf};
+
+use crate::error::{CliError, Result};
+
+/// 发现项目布局: BP/RP 目录 + scripts package 目录。
+/// 逻辑与 AbyssBossEngine tests/conftest.py 的自动发现一致。
+pub fn discover_layout(project_dir: &Path) -> Result<Layout> {
+    let behavior_pack = find_single_dir(project_dir, "behavior_pack_")?;
+    let resource_pack = find_single_dir(project_dir, "resource_pack_")?;
+    let scripts_package = find_scripts_package(&behavior_pack)?;
+    let scripts_package_name = scripts_package
+        .file_name()
+        .and_then(|n| n.to_str())
+        .ok_or_else(|| {
+            CliError::InvalidData(format!(
+                "scripts package 目录名非 UTF-8: '{}'",
+                scripts_package.display()
+            ))
+        })?
+        .to_string();
+
+    Ok(Layout {
+        behavior_pack,
+        resource_pack,
+        scripts_package,
+        scripts_package_name,
+    })
+}
+
+pub struct Layout {
+    pub behavior_pack: PathBuf,
+    pub resource_pack: PathBuf,
+    pub scripts_package: PathBuf,
+    pub scripts_package_name: String,
+}
+
+fn find_single_dir(parent: &Path, prefix: &str) -> Result<PathBuf> {
+    let mut matches = Vec::new();
+    for entry in std::fs::read_dir(parent)? {
+        let entry = entry?;
+        let path = entry.path();
+        if path.is_dir() {
+            if let Some(name) = path.file_name().and_then(|n| n.to_str()) {
+                if name.starts_with(prefix) {
+                    matches.push(path);
+                }
+            }
+        }
+    }
+
+    match matches.len() {
+        0 => Err(CliError::NotFound(format!(
+            "在 '{}' 下未找到 {}* 目录",
+            parent.display(),
+            prefix
+        ))),
+        1 => Ok(matches.into_iter().next().unwrap()),
+        _ => Err(CliError::InvalidData(format!(
+            "在 '{}' 下找到多个 {}* 目录",
+            parent.display(),
+            prefix
+        ))),
+    }
+}
+
+fn find_scripts_package(behavior_pack: &Path) -> Result<PathBuf> {
+    let mut matches = Vec::new();
+    for entry in std::fs::read_dir(behavior_pack)? {
+        let entry = entry?;
+        let path = entry.path();
+        if path.is_dir() && path.join("modMain.py").is_file() {
+            matches.push(path);
+        }
+    }
+
+    match matches.len() {
+        0 => Err(CliError::NotFound(format!(
+            "在 '{}' 下未找到含 modMain.py 的 scripts package",
+            behavior_pack.display()
+        ))),
+        1 => Ok(matches.into_iter().next().unwrap()),
+        _ => Err(CliError::InvalidData(format!(
+            "在 '{}' 下找到多个含 modMain.py 的目录",
+            behavior_pack.display()
+        ))),
+    }
+}
+
+/// PascalCase → snake_case: AbyssBossEngine → abyss_boss_engine
+pub fn pascal_to_snake(s: &str) -> String {
+    let mut result = String::new();
+    for (i, ch) in s.chars().enumerate() {
+        if ch.is_uppercase() && i > 0 {
+            result.push('_');
+        }
+        result.extend(ch.to_lowercase());
+    }
+    result
+}
+
+/// 首字母小写: AbyssBossEngine → abyssBossEngine
+pub fn lower_first_char(s: &str) -> Result<String> {
+    let mut chars = s.chars();
+    let first = chars
+        .next()
+        .ok_or_else(|| CliError::InvalidInput("name 不能为空".to_string()))?;
+    Ok(format!(
+        "{}{}",
+        first.to_lowercase().collect::<String>(),
+        chars.as_str()
+    ))
+}